Sorry, found a nasty glitch in the side surface of the "lock bolt" object. - might be an interesting puzzle for some of you to figure out.
Not that I understand a lot about the inner workings of the NURBS library, but you'd think glitchy surfaces would not be allowed, or at the least could be remedied more easily.

Plus, I rotated the model to where the bulk of the box is a flat-inclination.
Re-uploaded an updated model.